Or, at least I think it's the HVAC. The loud growl goes away whenever I turn the heater/aircon off.

The sound definitely seems to be coming from the passenger side of the car, perhaps underneath the dashboard. I found a mouse nest under there back in '11 right after I first got the car, so maybe something that was nibbled has gotten worse over the years?

I first noticed this growling sound this winter, but then it went away for a long time. Lately, it's been happening whenever I brake fairly hard and then it won't go away until I turn off the HVAC.

It's almost like a fan is unbalanced, something is grinding up against something else, or...who knows.

The dealership wants a bunch of money just to run diagnostics on it, so no, taking it to the dealer isn't an option right now. I've got a road trip across the country coming up next month and my A/C needs to work. Is this something I can rip apart and figure out myself?

I have zero idea what it could be, aside from narrowing it down to something HVAC-related. The dealer's service department mentioned that a bearing might be bad. It sort of sounds like something's rubbing against something else, or maybe a fan's whacking into something. Who knows. It's pretty worrisome, either way.

 

^
It's a quick & simple diagnosis - If you think it's A/C fan related >
1. Open your glovebox and disconnect the damper/shock and you should be able to see the fan unit.
2. There's a cabin filter latch, release it and remove cabin filter.


You should now be able to see the "squirrel" fan, use a flashlight and inspect the blades, make sure everything is legit and nothing is clogged or damaged.

NOTE: Be careful NOT to turn on your A/C when your hands (or anything else is in there) or when you're staring into the blower!

 

This is the sound, FWIW:


Thanks for the disassembly instructions! I'll tear into it soon and see what I find.

 

Sounds like your A/C fan blades are scratching up against something...
Perhaps the filter element itself have caved in (due to age or defect?)

 

i get the exact same damn thing. it bothers me alot. Im thinking of taking mine to the dealership before my warranty runs out .

 

Well, it's definitely not normal.
It could be the Texas heat, but it really does sound like blower grinding on/against something.

If you do take it up to the dealer, please let us know what they find out.

 

Sounds like the blower motor hitting something. Pull the glove box and filter as said before and check it out. It takes 2 mins to pull apart.

 

Next, pull the motor. It is easy. Inspect and look for debris and evidence of rubbing on the fan case.

 

All right, I couldn't stand it anymore, so I took the filter out and shook all the crap out. Takes less time than a morning poo break, so why not?

The closest thing I could find in there to a potential troublemaker was a blade of grass that was wedged along the outside. I don't know how it could be touching the fan itself since the round entry to the fan is inset a little way from that, but who knows. Maybe this is why it's only an issue sometimes and not all the time.

If that wasn't the issue, I may look into popping the fan itself out and giving it a good shake. Anywhere else to look that may be the source of the issue?

I stuck my hand down in the fan, manually spun it, and it didn't make any noises or have any resistance then. I didn't see any damaged blades, either. Weird.

 

^
Alright...
The next possibilities:
1. Could be the blower motor itself (Not the fan blades), motor/bearing failure? or, it would be loose in the housing.

2. The vent-motor/vane that controls the air circulation (the unit that directs the air flow up/down/windshield) may have failed, leading to it vibrating in the central vent tube. Rare, but possible.

3. Someone punked you > By shoving some scraps of paper into your air vents and now it's just flapping around in there when you have the A/C on...

 

I think it's the air circulation flap. We isolated that was where the noise was coming from, plus it's seemed kind of weak whenever I switch it from up to down sometimes.

I still have a noise. Replaced it with a brand new filter, still has a noise. At least I have a thing for the dealer to check when I take it in for a bunch of other crap today.